3 answers

Some would say that Ben's class names are presentational, rather than semantic, they might suggest that a class name should reflect its purpose, not its behaviour, so class="shout" or class="exclaim" would be better, but you might also use existing elements like <strong> and <em> and style those as uppercase and bold italic.

you could use javascript (jQuery) to parse the string, split on spaces into words, and wrap the words with spans with classes that are randomly assigned.
Or if you want to specify it in advance, just wrap the words in spans manually.